Process oe treating copper ores with ah



UNITED STATE PATET FFlCliZ.

NIELS C. CHRISTENSEN, 011 SALT LAKE CITY, UTAH.

PROCESS OF TREATING COPPER OIEtEE-i WITH. AN E102 SOLUTION FOR THE RECOVERY OF THE COPPER TIEEEREFROM.

No Drawing.

To all whom it may concern:

Be it known that I, NIELs C. CI-Ims'rnN- SEN a citizen of the United States, residing at Eialt Lake City, in the county of Salt Lake and State oi: Utah, have invented certain new and useful Improvements in Processes of Treating Copper Ores with an SO SOlIltion for the Recovery of the Copper Therefrom, of: which the following is a specification.

This invention relates to the lixiviation of oxidized ores of copper (or sulfid ores which have been roasted) with an S0 solution and the recovery of the copper from the solution. The invention relates particularly to the precipitation of the copper from the sulfite solution.

The lixiviation of the ore to secure the copper in solution may be carried out as described in my U. S. Patent #1278554, or preferably with the precautions described in my U. S. patent application #226523 so that it is not necessary to describe this part of the process in detail, except to repeat that the ore should be lixiviated with a relatively concentrated SO solution free from soluble sulfates. Thisoperation should preferably be carried out by agitating that ore with the S0 solution. After the copper has been brought into solution the pregnant solution should be removed from the lixiviated ore without long storage and without contact with air.

The object of my inventionis to precipitate the copper from the S0 solution as a cupro-cupric suliite without the formation of copper sulfate and to do this with reagents which are products of the process, and without theloss of any chemicals.

As described in my U. S. patent application #226523, I can accomplish this precipitation by adding metallic copper to the 011 50 solution and removing the excess S0 in the solution as shown below:

but this reaction takes place slowly and incompletely unless the solution is heated,

preferably to atleast 90 degrees C, and to Specification of Letters Patent.

Patented Nov. 9, 1920.

Application filed April 4, 1919. Serial No. 287,517.

lt is the objectof my invention to avoid this reduction to metallic copper and, if desired, to avoid the heating of the solution.

l avoid this reduction to metallic copper by substituting Cu O, instead of metallic copper, to precipitate the 011 80,, CuEaO as shown below:

CuSO +Cu O+SO :(M 550 cuso Cu SO ClusO -l-H O This reaction may be interpreted to be the same react-ion as occurs with metallic copper, the @11 0 being first acted upon by the sulfurous acid and the copper thus produced reacting with the CuSO to form the cuprocupric sulfite as shown below:

Cn O+H SO (Ct1+CuSO )+H O CuSO (Cu-P011550 =Cu SO CuSO This reaction takes place more completely at lower temperatures than the reaction with metallic copper, but may be carried out by heatin the solution and driving off the ex cess S 2 just vas with metallic copper.

If most of the excess S0 is first removed from the solution by heating or is drawn oil by applying a vacuum, leaving just enough S0 to complete the reaction, the copper may all be precipitated as the supro-cupric sulfite and all the S0 be removed'from solution without heating.

If it is not desired to remove the S0 from the solution by heating or by applying a vacuum, all the copper may be precipitated and all the S0 removed by adding a sufiicient excess oi? C11 0 to the cold solution to take up all the excess S0 as shown below:

2Cu O+2H SO (311 530 CuSO +Cu+2H O which might be written As shown in the above equations, only one half of: the metallic copper form is used up. The remainder is utilized in the roasting operation as later described.

thoroughly agitated so that the C11 0 re- 15 mains in suspension and reacts with the Cuqsfi so asto prevent the formatlon of X 1 I x (JuSu, which occurs when (A1 80, Cu :5 is precipitated merely by the removaloi' the excess SO, as shown in the following equation:

The Cu O necessary to precipitate the copper in my process is secured by heating the Cu SQ CuSO precipitate without access of air and preferably in. the presence of a reducing agent, such as carbon, hydrogen, hydrocarbons, copper, or other suitable reagents, to prevent the formation of CuSO as shown below:,

As before noted, an excess of C11 0 and S0 maybe used in the precipitation operation tnus securing an excess of metallic copper for use in the roasting operation as shown above. a

If an excess of reducing agent such as carbon or hydrocarbonsis used in. the roasting operation some of the (lu O may be reduced to metallic copper as the 011 0 is readily reduced but. this copper assists in the precipitation as indicated in the reactions shown and is therefore beneficial rather than detrimental in the process. It is ob vious from the equations given that a mixture of Cu O and metallic copper may be used in the process and the use of the mixture is advantageous in some cases, espe-' ciallywhen the solution is heated during the precipitation operation.

The roasting of the C11 SO CuSO precipitate is a Very simple operation as the sulfite is readily decomposed by heat. A few minutes heating with a reducing agent at 550 degrees 6.. is suflicient to drive oil all the SO, and form C11 0 as indicated.

The SO, from the roasting operation is used in the lixiviation of more ore as described in my U. ,S. patent application #226,523.

The advantages of my process are: first, that the C11 0 need not be reduced to metallic copper to secure the precipitation of the cupro-cupric suliite, also that if any of the (11 8 reduced in the roasting or heating operation the mixture oi 11,0 and metallic per acts just as ellicieutly as the Cu l); second, that the precipitation may be conducted either by heating the solution or with cold solutions, the latter avoiding the expense and diliiculties of heating the solution; third, that all the excess SO may be removed as well as practically all of the copper without heating the solution, thus giving a barren solution practically free from copper and chemical reagent which may be used for washing the ore in the lixiviation process.

From the foregoing description it is also seen that theoretically no reagents are necessary in my process after the first cycle of operations so that the only loss of reagent is that due to leakage and soluble material. other than the copper compounds, in the ore. The cheapness of the $0 the only reagent supplied to the process, makes the value lost extremely small.

Having described my process what I claim and desire to patent is:

l. The process of treating copper ores which consists in lirziviating the ore with an S0 solution, separating the pregnant solution from the lixiviated ore and adding C11 0 to said pregnant solution thereby precipitating the c pper from said solution as a cupro-cupric sulfite.

2. The process of treating copper ores which consists in lixiviating the ore with an Slil solution separating the pregnant solution from the lixiviated ore and removing some of the excess SO from said pregnant solution and adding Cu O thereby precipitating the copper as a cupro-cupric sullite.

3. The process of treating copper ores which consists in lixiviating the ore with an S0, solution separating the pregnant solution from the lixiviated ore, and heating said solution and driving off some of the excess S0 and adding C11 0 thereby precipitating the copper as a cupro-cupric sullite.

4i. The process of treating copper ores which consists in lixiviating the ore with an SO solution, separating the pregnant solution from the lixiviatcd ore, and adding C11 0 and metallic copper to said pregnant solution thereby precipitating the copper from said solution as a cupro-cupric sulfite.

5. The process of treating copper ores which consists in lixiviating the ore with an SO solution, separating the pregnant solution from the lixiviated ore, and adding Cu O to said pregnant solution thereby precipitating the copper from said solution as a cuprdcupric sulfite, and heating said cupro-cupric sulfite without access of air and driving off the S0 and using some of said so treated precipitate to precipitate more copper from pregnant solution.

6. The process of treating copper ores which consists in lixiviating the ore with an S0 solution separating the pregnant solution from the lixiviated ore and adding Cu O and metallic copper to said pregnant solution thereby precipitating the copper to from said solution as a cupro-cupric su and heating said precipitate without access of air and driving oil the S0 and using some of said so treated precipitate to precipitate more copper from pregnant solution.

7. The process of treating copper ores which consists in lixiviating the ore with an 30 solution, separating the pregnant solution from the lixiviated ore and adding Cu O to said pregnant solution thereby precipitating the copper from said solution as a cupro-cupric sulfite, and heating said cupro-cupric sulfite without access of air and in the presence of a reducing agent and driving off the S0 and using some of said so treated precipitate to precipitate more copper from pregnant solution. 7

8. The process of precipitating the copper from an S0 solution which consists in adding Cu O to said solution.

9. The process of precipitating the copper from an S0 solution which consists in adding Cu f) and metallic copper to said solution.

10. The process of removing SO from an S0 solution which consists in adding cuprous oXid to said solution and thereby precipitating the S0 in combination with the copper as a cupro-cu'pric sulfite.

11. he process of recipitating the copper and removing the from an S0 solution which consists in adding Cu O to said solution.

12. The process of treating copper ores which consists in lixiviating said ore with an S0 solution, separating the pregnant solution from the lixiviated ore and adding to said solution cuprous oXid, thereby precipitating the copper as a cupro-cupric sullite and removing the S0 from solution as a cupro-cupric sulfite.

13. The process of treating copper ores which consists in lixiviating said ore with an SO solution, separating the pregnant solution from the lixiviated ore and adding cuprous oxid, thereby precipitating the copper as a cupro-cupric suliite and removing the S0 from solution as a cupro-cupric sulfite and heating said precipitate without access of air and driving off the S0 and using said S0 in the treatment of more ore.

1 1-. The process of treating copper ores which consists in lixiviating said ore with an S0 solution, separating the pregnant solution from the lixiviated ore and adding cuprous oXid, thereby precipitating the cop per as a cupro-cupric sulfite and removing the S0 from solution as a cupro-cupric sulfite and heating said precipitate in the presence of a reducing agent and without access of air and driving off the excess S0 and using said SO in the treatment of more ore, and using said so treated precipitate to precipitate more copper from pregnant solution.

NIELS C. CHRISTENSEN. 

